The Effects of Chronic Exposure to Low-Level Blasts

Completed

• Conditions: Tramatic Brain Injury

• Registration Number: NCT01524822
• Lead Sponsor: National Institute of Neurological Disorders and Stroke (NINDS)

Brief Summary

Background:

- Repeated exposure to explosions may lead to changes in the way that people think or feel. Breachers (people trained to use explosives to get into buildings) are exposed to repeated blasts as part of their job. Researchers want to study how they might be affected by blast exposure. Breachers will be compared with other groups who have different levels of exposure to repeated blasts. Information will also be obtained from spouses or close companions.

Objectives:

- To study the effects of repeated exposure to low-level blasts on thinking, memory, behavior, and brain function.

Eligibility:

* Experienced military and civilian breachers, experienced active duty artillery operators, and active duty military without frequent blast exposure, 18 and 60 years of age.

* Spouses or close companions of these individuals.

Design:

* Participants will be screened with a physical exam and medical history. Blood samples will be collected and a urine pregnancy test will be required of participants (not companions) before MRI scanning.

* Participants will spend up to 5-days as a NIH clinic outpatient, with about 6 hours of tests each day. Tests will include the following:

* Medical and professional history, with questions about exposures to blasts

* Tests of thinking, memory, and concentration

* Balance tests

* Hearing tests

* Imaging studies, such as magnetic resonance imaging, to look at the brain

* Overnight sleep study to monitor brain waves

* Blood samples

* Participants will return 1 year later for a 3-day followup visit. Some of the tests from before will be repeated. A spouse or close companion (if available) will be asked to complete questionnaires or have a telephone interview....

Detailed Description

The purpose of this study is to evaluate the cognitive and neurophysiological effects of chronic exposure to repeated low-level blast overpressure. Previous studies show converging evidence for a neurophysiological effect from cumulative exposure to blast, which is consistent with subjective reports of cognitive impairment by individuals trained to use explosives to gain entry to structures (breachers). This study will expand on these findings by examining a larger cohort of experienced breachers and artillery personnel who may be incurring a cumulative effect of low-level blast exposure over the course of several years. We will evaluate up to 20 participants from each of three groups: breachers, artillery personnel, and unexposed individuals. Additionally, we will ask each of the above to bring a close companion for a set of questionnaires and an interview to capture changes in functioning that participants may not be able to self-assess. Participants will travel to the NIH for evaluation of cognitive and neurophysiological measures. The procedures include neuropsychological testing, blood analysis for biomarkers, vestibular and auditory testing, and neuroimaging studies using diffusion tensor imaging, susceptibility weighted imaging, perfusion imaging, functional magnetic resonance imaging, and, where there is evidence of a sleep disorder, polysomnography. This study will be conducted in collaboration with the Naval Medical Research Center (NMRC) and the Walter Reed Army Institute of Research (WRAIR) under a Research Collaborative Agreement. The complementary DoD protocol will be reviewed by the DoD IRB and includes this NIH protocol. The complementary DoD protocol includes data collection at field settings, activity NIH is not engaged in and not described in this protocol.

Study Timeline

• Study First Submitted: 2012-01-31
• Study First Submitted QC: 2012-01-31
• Study First Posted: 2012-02-02
• Study Start: 2012-07-30
• Status Verified: 2023-03-14
• Last Update Submitted: 2023-03-16
• Last Update Posted: 2023-03-17

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 66

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
computer-based standardized testing, specifically the ANAM battery and the Simple Reaction Time (SRT) subtest within that battery	10 years	The primary objective for this study is based on anecdotal report of blast-related symptomology and previous and ongoing studies with the breacher community, suggesting a relation between post-concussive symptomology and chronic exposure to low yield blast. Measures employed in this protocol are based on measures used in other protocols in this line of research, measures used inmilitary clinical practice for concussion, and measures outlined in literature as sensitive to brain injury. These include neuroimaging procedures (fMRI, DTI, SWI, and Gadolinium contrast), neurocognitive testing, and vestibular testing.

Secondary Outcome Measures

Name	Time	Method
blood draw and analysis for biomarkers of brain injury and tests of peripheral auditory functioning and polysomnography to address potential confounds.	10 years	The secondary objectives for this study are intended to be complementary to the primary research questions and are considered important supporting data. These include blood analysis for biomarkers of brain injury, tests of peripheral auditory functioning, and polysomnography.

Trial Locations

Locations (1)

National Institutes of Health Clinical Center; 🇺🇸 Bethesda, Maryland, United States